How to Print a PDF Sewing Pattern at the Correct Scale (and Fix the Test Square)

Quick answer: the test square on a sewing pattern is a 10cm × 10cm (or 2in × 2in) box printed specifically so you can check your printer didn't scale the pattern. Print just the first page, measure the square with a ruler, and if it's off by even a couple of millimeters, your printer or PDF viewer is set to "Fit to Page" instead of "Actual Size" — go back into your print settings, force 100%/actual size, and print the test page again before printing anything else.

Here's why this matters more than almost any other step in the whole process, and exactly how to fix it in the apps people actually use.

Why patterns include a test square in the first place

Printers and PDF viewers are designed to be helpful by default — if a page is slightly too big for the paper, they'll quietly shrink it to fit, usually to somewhere around 90–97% scale. That's a sensible default for a letter or a spreadsheet. For a sewing pattern, it's exactly the failure mode you need to catch, because a garment piece measuring 40cm across printing at 97% comes out at 38.8cm — small enough to throw off a fit, but not obvious just by looking at the page.

The test square exists to make that invisible error visible. It's a fixed, known size — conventionally 10cm × 10cm or 2in × 2in — so a ruler is all you need to confirm whether your printer respected the pattern's true scale or quietly adjusted it.

How to measure the test square correctly

1. Print only the page containing the test square first — not the whole pattern.
2. Let the ink fully dry/set for a few seconds (paper can shift slightly right off the printer).
3. Lay a ruler across the square and measure edge to edge.
4. Compare against the labeled size: exactly 10cm, or exactly 2 inches.

If it matches, your settings are correct — print the rest of the pattern using the exact same settings, in the same sitting if possible. If it's short, even by a millimeter or two, something in your print pipeline is scaling the page down, and you need to fix that before printing further.

Setting your printer or PDF viewer to 100% scale

The setting you need is usually called Actual Size, 100%, or Custom Scale: 100 — never "Fit to Page," "Shrink to Fit," or "Scale to Fit," which are the settings that cause the problem in the first place.

• Adobe Acrobat / Reader: In the print dialog, look under Page Sizing & Handling and choose Actual Size. According to Adobe's own documentation, this option prints the page without any scaling applied. Avoid "Fit," which Adobe describes as an option that resizes each page to match the printable area — the opposite of what you want here.
• Mac Preview: In the print dialog, select Scale and enter 100. Apple's own support guide confirms this is done by choosing Scale and entering a percentage directly — a separate setting from "Scale to Fit," which instead expands or shrinks the page to match the paper.
• Google Chrome (viewing a PDF): Open the print dialog, click More settings, and set Scale to Custom → 100. Chrome sometimes defaults to "Fit to page" for PDFs, so this needs to be checked explicitly rather than assumed.
• Windows / other PDF viewers: Look for wording like Actual size, 100%, or Do not scale in the print dialog — the exact label varies by app, but the underlying setting is the same one described above.

Set this once, print your test square page, confirm the measurement, then print the rest of the pattern without changing anything in between.

What if the square still measures wrong after setting 100%?

A few less-common causes, if you've already set actual size/100% and the square is still off:

• Printer driver scaling. Some printer drivers apply their own "fit to printable area" setting independently of the app's print dialog — check your printer's own settings/preferences window, not just the app's print dialog.
• A previous scale setting stuck. Some apps (Acrobat Reader in particular) remember the last scale you used and reapply it automatically next time, so double-check the field shows 100 rather than assuming it reset.
• The PDF itself was pre-scaled. If a pattern was poorly converted from A0 to A4 without preserving true scale — as opposed to a proper re-tiling that keeps every dimension exact — no printer setting can fix that, because the error is baked into the file. In that case the fix is re-converting the file correctly, not adjusting your printer.

A quick sanity check beyond the test square

If a pattern doesn't include a test square at all, you can still catch a scaling error: measure any dimension given as an exact figure in the pattern's own instructions — a seam length, a finished garment measurement, anything stated precisely — against your printed page. The principle is identical: compare a known number to a ruler before you trust the print.

Frequently asked questions

What size should a sewing pattern's test square be?+

Most patterns use either a 10cm × 10cm square or a 2-inch × 2-inch square (sometimes a straight 2-inch reference line instead of a full square). Check the label on your specific pattern's test square — the pattern will state which measurement to check against.

Why does my printer keep shrinking my PDF even though I didn't ask it to?+

Most printers and PDF viewers default to a "Fit to Page" or "Shrink to Fit" scaling mode, since it's a sensible default for most documents. You need to explicitly switch this to "Actual Size" or "100%" in the print dialog — it usually isn't the default and has to be selected every time unless your app lets you save it as a preset.

I set my printer to 100% and the square is still wrong — what now?+

Check your printer's own driver settings (not just the app's print dialog) for a separate scaling option, confirm the app didn't silently revert to a remembered setting, and rule out that the PDF itself was scaled incorrectly during an earlier A0-to-A4 conversion. If the file itself was mis-converted, no printer setting will fix it — the file needs to be re-tiled correctly.

Can I trust the test square if I'm printing from my phone?+

Yes, the same principle applies — measure the printed square with a ruler regardless of what device sent the print job. Mobile print apps have their own scaling quirks and defaults, so it's worth checking the test square just as carefully as you would printing from a computer.

Does this matter if I'm just projecting my pattern instead of printing it?+

No — the test square and 100% scale settings are specific to home printing. Projector-based sewing uses a completely different calibration method, since there's no printed page to measure. See our note on projector sewing if that's your workflow instead.

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If you're starting from a large-format A0 file rather than an already-tiled pattern, make sure the conversion itself preserved true scale before you even get to the printer settings above — see how to convert an A0 copyshop pattern to A4. TileMyPattern builds a test square into every tiled PDF it generates automatically, so this check is baked into the workflow from the start rather than something you have to add yourself. For the full print-and-assemble process after your scale is confirmed, see how to print and assemble a PDF sewing pattern at home.